It's got an adorable hero from an iconic media brand who is voiced by a proven box office master at snark. But, somehow, "Pokémon Detective Pikachu" never really gets arresting.

Ryan Reynolds (voicing the titular Pokémon) tries hard but can't make this live action-meets-animated movie gel. It's plodding and listless and really not funny or smart enough. Turns out, you can't copy "Deadpool" tricks for the PG set.

"Pokémon Detective Pikachu" borrows lightly from film noir crime dramas to create a mystery in a world where humans and Pokémon co-exist. A young man called Tim Goodman (the terrific Justice Smith) joins with Pikachu to search for what happened to the man's father, a missing detective. The movie's best moments are those between the scenes, where the Japan-born creatures thrillingly share the same urban space as humans.

Ken Watanabe and the pokemon Snubbull in a scene from 'Pokemon Detective Pikachu'

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Smith is very appealing as a son coming to grips with the loss of his estranged father, but Reynolds, as a cute coffee-guzzling detective with a Sherlock Holmes' deerstalker cap, ping-pongs from heartfelt to caustic uneasily and tries to mimic his best-known, fourth-wall breaking "Deadpool" movie character ("That's a twist. Very twisty," he says of one plot point.) It's the most mismatched buddy flick since Will Smith teamed up with an Orc for "Bright."

The film starts slowly, builds to a sort of plateau and then ends with the final third consisting of nonstop action sequences and an underwhelming conclusion. Ken Watanabe is underused as a police chief. Equally inexplicably, Suki Waterhouse gets credit for a role in which she never speaks and lasts about 15 seconds onscreen.

Speaking of speaking, you're probably wondering why there's any dialogue between the adorable pocket monsters and humans since Pokémon traditionally only just say their own names. Enter five screenwriters — Rob Letterman, Dan Hernandez, Benji Samit, Derek Connolly and Nicole Perlman. Their solution is a weird gas that makes everyone crazy but somehow allows Tim to communicate with Pikachu. Sure, gas.

In what's probably a completely fair fight, Detective Pikachu (voiced by Ryan Reynolds) tangles with a Charizard in the new movie 'Pokemon Detective Pikachu.'

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The pair are joined by a junior reporter — really an unpaid intern tasked with writing listicles, played by a winning Kathryn Newton — who helps them get to the bottom of the mystery using shoe leather and guile. (This is a film that celebrates the media in a big way — there are newspaper clippings, honorable TV reporting and a respected giant cable network. "It's not news if it can't be verified," says one character. Take that, fake news people.)

But it's all a bit of a muddle. We meet some cool Pokémon — Charizard, Psyduck, Snubbull, Ditto, Magikarp, Cubone and Mewtwo — mixed in with a climate change joke and an attempt to burn a miming Pokémon with mimed gasoline. It's a film that explores daddy issues and also riffs off "Silence of the Lambs" ("Are you gonna make me into a lampshade?" Pikachu asks his human minder). Some of it is very scary for younger kids; most of it is incomprehensible to adults.

Justice Smith, left, the character Detective Pikachu, voiced by Ryan Reynolds, and Kathryn Newton in a scene from 'Pokemon Detective Pikachu'

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Then there's Rita Ora playing a research scientist. We're not sure why that is but she also teams up with Kygo to supply the film's signature song "Carry On" — a bland, lazy, derivative club banger. It's perfect for this flat film.

Live-action feature film adaptations of video games have proved a dicey proposition in the past. For every "Mortal Kombat" there's a "Prince of Persia." This one just feels like a venal money grab from a mega corporation.